Spring Boot 中自定义接口返回格式

待我称王封你为后i 2022-01-11 05:55 543阅读 0赞

# Spring Boot 中自定义接口返回格式 #

> Spring Boot 项目中提供的 REST 接口往往需要封装状态或者其他附加的内容返回给客户端，如果每个接口都用一些工具类来处理很繁琐，会增加很多重复代码，还有可能漏掉导致客户端无法解析；用切面也可以实现，但是 SpringBoot 提供了处理的接口

### 项目地址 ###

[https://github.com/helloworlde/SpringBootCollection/tree/master/SpringBoot-CustomResponse][https_github.com_helloworlde_SpringBootCollection_tree_master_SpringBoot-CustomResponse]

### 添加自定义注解 ###

*  CustomResponse.java

import java.lang.annotation.*;
    
    @Target(ElementType.METHOD)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface CustomResponse { 
    }

### 消息内容 ###

封装返回内容的实体

*  CustomResponseContent.java

@Data
    @Builder
    @NoArgsConstructor
    @AllArgsConstructor
    public class CustomResponseContent { 
    
        private Integer code;
    
        private String status;
    
        private Object data;
    
        private String message;
    }

### 返回内容处理器 ###

用于封装返回内容

*  CustomResponseReturnValueHandler.java

public class CustomResponseReturnValueHandler implements HandlerMethodReturnValueHandler, AsyncHandlerMethodReturnValueHandler { 
    
        private static final ObjectMapper objectMapper;
    
        static { 
            objectMapper = new ObjectMapper();
            objectMapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
            objectMapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
            objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
        }
    
        @Override
        public boolean isAsyncReturnValue(Object o, MethodParameter methodParameter) { 
            return supportsReturnType(methodParameter);
        }
    
        @Override
        public boolean supportsReturnType(MethodParameter methodParameter) { 
            return methodParameter.getAnnotatedElement().getAnnotation(CustomResponse.class) != null;
        }
    
        @Override
        public void handleReturnValue(Object data, MethodParameter methodParameter, ModelAndViewContainer modelAndViewContainer, NativeWebRequest nativeWebRequest) throws Exception { 
            modelAndViewContainer.setRequestHandled(true);
            HttpServletResponse response = nativeWebRequest.getNativeResponse(HttpServletResponse.class);
            response.setContentType(MediaType.APPLICATION_JSON_UTF8_VALUE);
    
            String message = "操作成功";
            String status = "success";
    
            if ((data instanceof Boolean) && !((Boolean) data)) { 
                message = "操作失败";
                status = "fail";
            }
    
            CustomResponseContent responseContent = CustomResponseContent.builder()
                                                                         .code(response.getStatus())
                                                                         .status(status)
                                                                         .message(message)
                                                                         .data(data)
                                                                         .build();
    
            response.getWriter()
                    .write(objectMapper.writeValueAsString(responseContent));
    
        }
    }

### 添加配置 ###

将返回值处理器添加到应用中

*  CustomWebMvcConfigurer.java

@Configuration
    public class CustomWebMvcConfigurer implements WebMvcConfigurer { 
    
        @Override
        public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> handlers) { 
            handlers.add(new CustomResponseReturnValueHandler());
        }
    }

## 测试 ##

### 添加接口 ###

*  ProductController.java

@RestController
    public class ProductController { 
    
        private static Map<Long, Product> productMap;
    
        static { 
            productMap = Stream.of(
                    Product.builder().id(1L).name("product1").price(1L).build(),
                    Product.builder().id(2L).name("product2").price(2L).build(),
                    Product.builder().id(3L).name("product3").price(3L).build()
            ).collect(Collectors.toConcurrentMap(Product::getId, p -> p));
        }
    
        @GetMapping("/boolean")
        @CustomResponse
        public Boolean getBoolean(String booleanValue) { 
            return "true".equals(booleanValue);
        }
    
        @GetMapping("/product/{id}")
        @CustomResponse
        public Product getProduct(@PathVariable Long id) { 
            return productMap.get(id);
        }
    
        @GetMapping("/product")
        public List<Product> getProducts() { 
            return new ArrayList<>(productMap.values());
        }
    }

### 测试 ###

# 没有添加自定义返回值注解
    curl localhost:8080/product
    
    [{ "id":1,"name":"product1","price":1},{ "id":2,"name":"product2","price":2},{ "id":3,"name":"product3","price":3}]%
    
    # 添加了自定义返回值注解
    curl localhost:8080/product/1
    
    { "code":200,"status":"success","data":{ "id":1,"name":"product1","price":1},"message":"操作成功"}%
    
    # Boolean 值返回不容的状态
    curl 'http://localhost:8080/boolean?value=true'
    { "code":200,"status":"success","data":true,"message":"操作成功"}%
    
    curl 'http://localhost:8080/boolean?value=false'
    { "code":200,"status":"fail","data":false,"message":"操作失败"}%

[https_github.com_helloworlde_SpringBootCollection_tree_master_SpringBoot-CustomResponse]: https://github.com/helloworlde/SpringBootCollection/tree/master/SpringBoot-CustomResponse